Fin winding machines



April 1966 R. M. STIKELEATHER 3,247,696

FIN WINDING MACHINES 2 Sheets-Sheet 1 Filed March 18, 1963 April 26, 1966 R. M. STIKELEATHER FIN WINDING MACHINES 2 Sheets-Sheet 2 Filed March 18, 1963 6y WJ (7% j United States Patent 3,247,696 FIN WINDING MACHINES Robert M. Stikeleather, 324 N. Franklin St. Holbrook, Mass. Filed Mar. 18, 1963, Ser. No. 265,897 3 Claims. (Cl. 72-436) This invention relates to heat exchange tubes having extended surface fins wound spirally thereon, and to mechanism for crimping the outer portion of a fin as it is wound on a tube.

My U.S. Patents Nos. 2,713,375 and 2,799,389 disclose how metal ribbons can be wound spirally on tubes by thinning their outer portions so that the ribbons are caused to curl about and adhere to the tubes. During the thinning of the outer portion of such a ribbon, a wave is formed in the fin, and my said patents disclose how such a wave can be removed from a fin for providing a fin having a smooth surface.

While smooth fins are preferred for some applications, in other applications, increased heat transfer is preferred to the reduced air resistance of smooth fins. The inner portions of the fins, those portions closest to the tube surfaces, are, of course, heated or cooled more than are the outer portions of the fins, but they have more surface exposed to air flowing parallel to the fins than the outer fin portions, and, therefore, offer more resistance to the air flow than do the outer fin portions. This results in more air passing the outer fin portions and less air passing the inner fin portions than would be the case if the resistances were equal.

This invention increases the amplitude of a wave produced in a fin during the thinning of its outer portion, for providing increased slack in the outer fin portion, and provides radially extending crimps in such outer portion, absorbing the slack. The crimps decrease the spacing between the outer portions of the turns of a fin, constricting the air passages between such outer portions so that the air volume passing the inner fin portions is increased.

' The crimps also provide increased heat transfer surface,

and create turbulence in air flow which causes the boundary layers of insulating air to be removed from the fin surface.

An object of this invention is to add additional surface to a spirally wound fin on a heat transfer tube.

Another object of this invention is to place radially extending crimp-s in the outer portion of a fin wound spirally on a heat exchange tube.

Another object of this invention is to place radially extending crimps in the outer portion of a fin as it is being wound spirally on a heat exchange tube.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a plan view looking downwardly upon a fin winding machine embodying this invention;

FIG. 2 is an enlarged fragmentary view of the fin deforming rolls and of the crimp forming rolls of the machine;

FIG. 3 is an enlarged side view of a turn of a fin formed in the machine;

FIG. 4 is an enlarged fragmentary cross-section through the fin of FIG. 3;

FIG. 5 is an enlarged view of the toothed driving end of the smaller crimping roll of the machine;

FIG. 6 is an enlarged view of the other end of the roll of FIG. 5, showing the rounded crimping edges which with corresponding edges of the larger crimping roll of the machine, crimp the outer portion of the fin as it is wound on a tube;

FIG. 7 is a fragmentary, enlarged view of the toothed driven end of the larger crimping roll of the machine, and

FIG. 8 is a fragmentary, enlarged view of the other end of the roll of FIG. 7, showing its fin crimping edges.

A conventional, tube rotating and advancing mechanism 10 such as is disclosed in my Patent No. 2,713,375, is attached to a frame 11, and rotates and advance-s a tube 12. A metal ribbon is fed by means which is not shown but which is shown in my said patents, between conventional tapered rolls 13 and 14 on shafts 15 and 16 respectively.

An electric motor 17 drives through pulleys 18 and 19 and a belt 20, a conventional, speed reducing, gear box 21. A pulley 22 on a shaft 23 of the gear box, drives through a belt 24, pulley 25 of the mechanism 10. Pulley 28 on shaft 29 of the gear box, drives through a belt 30, pulley 31 on the shaft 15. The shaft 15 has a gear 32 on its outer end which meshes with a gear 33 on the shaft 16. The shafts 15 and 15 are supported within bearing housings 35 and 36 respectively, attached to the frame 11. The shaft 29 is supported within bearing housings 38 attached to the frame 11.

On the opposite side of the tube 12 from the rolls -13 and 14 are crimp forming, small roll 40, and crimp forming, large roll 41. The roll 40 is on a shaft supported within bearing housing 42 attached to the frame 11, and has a pulley 43 attached thereto which is driven through a belt 44 by a pulley 46 on the shaft 29. The roll 41 has a shaft 48 supported within bearing housing 49 attached to the frame 11. The roll 40 has gear teeth 50 on one end which mesh with gear teeth 51 on the corresponding end of the roll 41. On the other end of the roll 40 are spaced-apart, rounded edges 54 milled from the teeth 50 at their centers, which extend midway between corresponding rounded edges 55 which have been milled from the teeth 51 at their centers. The end of the roll 41 where the edge-s 53 are formed, is recessed to clear turns of fin 57 on the tube 12. The axis of the roll 41 is placed at a slight angle to the axis of the roll 40 so that inner end 56 of the roll 41 around the recess in the latter can clear the second turn of the fin 57 and so that the roll end 56 can extend between the first and second turns of the fin 57 as shown by FIG. 2.

Operation In operation, the motor 17 drives through the pulleys 18 and 19 and the belt 20, the gears within the gear box 21, which drive through the pulleys 22 and 25 and the belt 24, the tube rotating and advancing mechanism 10. The gears within the gear box drive through the pulleys 28 and 31 and the belt 3f the shaft 15 of the roll 13. The shaft 15 drives through the gears 32 and 33, the shaft 16 of the roll 14. The gears within the gear box drive through the shaft 29, the pulleys 46 and 43 and the belt 44, the shaft 45 of the roll 40. The gear teeth 50 of the roll 40 drive through the gear teeth 51 of the roll 41, the roll 41.

A metal ribbon which is not shown, is supplied between the rolls 13 and 14 as described in my said patents, and its outer portion is thinned so that it curls about and adheres to the tube 12 as the latter is rotated and advanced by the mechanism Ill, forming turns of the fin 57. The rolls 13 and 14 differ from the corresponding rolls disclosed in my patents only in that they deform the ribbon more for increasing the amplitude of the waves formed in the outer portion of the fin for providing slack to be taken up by the formation of crimps.

The outer portion of the first turn of the fin as it is wound on the tube, passes between the rolls 40 and 41, and the edges 54 and 55 respectively, of the latter, crimp the outer fin portion, forming radially extending crimps 60 therein which extend both ways from each turn of the fin. The inner portion of each turn of the fin is smooth since the wave formed by the rolls 13 and 14 occurs only in the outer fin portion. The edges 54 and 55 preferably are rounded for preventing the cutting of the fin when it is crimped.

The crimps 60 constrict the space between the outer portions of adjacent turns of the fin, causing the air volume passing the inner fin portion to increase for increasing heat transfer between the air and fin; provide additional heat exchange surface, and create turbulence in the air passing between the fin turns for removing boundary layers of insulating air from the fin. These all add up to greatly increased heat transfer over that present where smooth fins are used.

What is claimed is:

1. In a fin Winding machine having means for rotating and advancing a cylindrical tube, and having a pair of deforming rolls at one side of said tube for thinning the outer portion of a metal ribbon for causing said ribbon to curl about and to adhere to said tube so as to be spirally ribbon for causing said ribbon to curl about and adhere to said tube so as to be spirally wound thereon, the combination of a pair of crimping rolls having corresponding ends near said tube and having spaced-apart edges around end portions at said ends, said edges being located to receive between the edges on one of said crimping'rolls and said edges on the other of said crimping rolls, the outer portion of the first turn of a fin wound on said tube, one of said crimping rolls being a relatively small roll and having an axis at a right angle to the axis of said tube, the other one of said crimping rolls being a relatively large roll and having an axis at a slight angle to the axis of said small roll, said large roll having a recess at its said end and having an end portion around said recess which extends into the space between the first and second turns of a fin wound on said tube and having its said edges around said end portion.

3. The invention claimed in claim 2 in which said crimping rolls have meshing gear teeth formed around their other ends, and in which means is provided for driving one of said crimping rolls.

References Cited by the Examiner UNITED STATES PATENTS 242,300 5/1881 Gold 165184 2,532,239 11/1950 Newlin 7213 7 2,654,124 10/1953 Layte 72136 2,667,337 1/1954 Chapman 165184 2,799,389 7/1957 Stikeleather 72137 2,812,794 11/1957 Chapman 72136 3,148,441 9/1964 Schuler 72-136 CHARLES W. LANHAM, Primary Examiner.

FREDERICK L. MATTESON, JR., Examiner.

W. H. JUST, Assistant Examiner. 

1. IN A FIN WINDING MACHINE HAVING MEANS FOR ROTATING AND ADVANCING A CYLINDRICAL TUBE, AND HAVING A PAIR OF DEFORMING ROLLS AT ONE SIDE OF SAID TUBE FOR THINNING THE OUTER PORTION OF A METAL RIBBON FOR CAUSING SAID RIBBON TO CURL ABOUT AND TO ADHERE TO SAID TUBE SO AS TO BE SPIRALLY WOUND THEREON, THE COMBINATION OF MEANS AT THE OPPOSITE SIDE OF SAID TUBE AND OPPOSITE SAID DEFORMING ROLLS FOR FORMING RADIALLY EXTENDING CRIMPS IN THE OUTER PORTION OF THE FIRST TURN OF SAID FIN WHILE IT IS BEING WOUND ON SAID TUBE. 